We owe plankton a lot. They built the Cliffs of Dover, they nourish the largest and smallest animals in the ocean, and they provided half of the oxygen you’re breathing right now. Yet these microscopic sea creatures remain mostly a mystery. A new global atlas of ocean plankton hopes to change that. MAREDAT is an international collaboration combining more than half a million pieces of data to create the most comprehensive map of the what, where, and when of plankton in the world’s oceans.